Flooring my shed - suggestions?

[Stephen Gilkes]

I need to floor the concrete base of my shed to make it habitable as an "office". There is no damp problem and the concrete is pretty thick.

I was thinking that I could fit 40x50mm joists directly to the concrete using screws and plugs every 60cm. Between the joists I would lay 35mm Celotex (left over from the insulating the walls). Then on top of that I could lay some kind of flooring. I originally intended to lay chipboard "loft" floor boards then carpet it.

However I'd rather lay some kind of wooden floor. Should I still fit the chipboard then lay the wooden floor on top of that?

Any help would be greatly appreciated!

[Grunff]

Sounds like a good plan - though I think 60cm is a little too far. 40cm is good, 50cm probably ok.

It's a good idea to lay some DPM over the concrete before you screw in the joists.

I's probably use 3/4" exterior grade ply for the floor, then finish with whatever I want. I'm not a fan of chipboard, especially if there's any chance of high humidity.

Depends on what the wooden floor is - if you use T&G softwood floorboards then it's not necessary, they can go straight onto the joists.

[Stephen Gilkes]

DPM = Damp Proof Membrane?

Whats the best way of doing this?

If I just layed T&G softwood floorboards onto the joists would I just need to varnish them and that would be it?

[Grunff]

Yes.

It's just a thick polythene sheet - you buy it from a BM (builders merchant) and lay it out onto the concrete.

That's entirely up to you. Main thing to bear in mind is that untreated softwood floorboards will a. scratch and dent easily and b. absorb stains easily. Varnishing eliminates b. and helps a little with a., but is by no means necessary.

[Stephen Gilkes]

[Andy Hall]

For my workshop I used the strip form of DPM normally used in walls.

In this application it strikes me that it might be better to do this rather than covering the entire concrete floor and to arrange some ventilation below the insulation - e.g. a couple of air bricks in the wall; and to arrange the joists in an alternating pattern so that air can move through. For belt and braces, pressure treated joists and then spray the underside of the boards with clear solvent based preservative.

.andy

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[Stephen Gilkes]

Just been looking at flooboards on the web. I also spoke to a chap at Wood2U.com and he recommended this:

"The floor is unfinished constructed on plywood faced with a 6mm thick solid Oak wear layer and a bevelled edge. Price per metre £35.75"

Now this seems hard wearing and stable (the "office" will get cold at night) but a little pricey. Any recommendations?

[Andy Hall]

If you want oak, you can get solid 22mm T&G floor boards for around £30/m^2.

Much better value for money and will last somewhat longer.

.andy

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[Stephen Gilkes]

Not sure if I want Oak or not.

Just want the best combination of price and durability. I have approx 10m^2 to cover and would like to spend around £150.

[Andy Hall]

You probably won't get much in hardwood for £15/m^2.

That's closer to laminate prices, but of course laminate looks like.. well.. laminate.

.andy

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[Stephen Gilkes]

Laminate would be OK. It just has to be OK in an environment where it might get very cold at night then warm through the day.

I would like to be able to nail it to the "joists". Is this possible with laminate?

If I cant nail it to the "joists" would I have to screw (or nail) chipboard floor panels to the joists then glue the laminate to the chipboard?

[Stephen Gilkes]

Would pine floorboards be OK? Or will they buckle with the changes in temperature

[Grunff]

As much as I like laminate (sorry Andy, but I do!), I wouldn't use it in a shed. Unless it's bathroom grade stuff.

[Grunff]

No, you can't nail it - it has to be laid as a floating floor. Otherwise it will definitely distort.

[Grunff]

It's the accompanying changes in humidity that may cause problems. But the worst that will happen is that small gaps will appear between the boards. That's softwood floor boards for you.

This is why I like ply - it really is dimentionally stable.

[Andy Hall]

You would need to lay a floor of chipboard or ply first and fit the laminate to that.

.andy

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[Andy Hall]

That would be OK as long as you buy properly dried boards. The main effect is through changes in humidity rather than temperature.

.andy

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[Andy Hall]

I'm not sure that it's suitable for being laid unsupported anyway is it?

.andy

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[Grunff]

No, i'd lay it floating on top of 3/4" ply.

[Mike Mitchell]

Laminate is marvellous! It has transformed my three bedrooms where before there were horrid old floorboards. Now the floors look the best part of the rooms. And cheap, too.

MM